DOWNSHIFT IN HYDROSTATIC DRIVE WORK MACHINE

PROBLEM TO BE SOLVED: To provide downshift in a hydrostatic drive work machine. SOLUTION: This invention relates to the hydrostatic drive work machine, and a method and control module having a control algorithm for performing a downshifting event in the work machine. The method includes the step of inducing a retarded mode in the work machine, if upon commanding the downshift the work machine is not in the retarded mode. The method further includes the steps of adjusting displacement of each of a variable displacement pump and a variable displacement motor in a hydrostatic drive of the work machine, and of increasing pressure on a low clutch of the work machine. The control algorithm includes a means for inducing the retarded mode in the work machine, if the work machine is not in the retarded mode upon commanding the downshift, with at least one of the variable displacement motor and the variable displacement pump in the hydrostatic drive of the work machine. COPYRIGHT: (C)2006,JPO&NCIPI